In a note to investors, they predicted 14 million iPhone X shipments for the first three months of 2018, then just 7 million shipments for the second quarter. That's down from 32 million for the last quarter of 2017, when the phone went on sale.

These are the most pessimistic numbers we've seen yet, as analysts race to downgrade their iPhone X shipment forecasts. In December, some analysts estimated shipments of about 25 million units in the first quarter alone.

Here's what Citi's analysts wrote, emphasis ours:

"We reduce our 1Q18E and 2Q18E iPhone build forecast mainly due to sluggish iPhone X demand. For 1Q18E, we now forecast overall iPhone shipment of 51m vs. 61m previously. We reduce 1Q18E iPhone X shipment to 14m from 27m. For 2Q18E, we trim total iPhone shipment to 40m from 48m previously as we revise down iPhone X shipment to 7m. Overall, we now model 1H18E total iPhone build of 92m vs. 85m in 1H17E, up 7% [year on year]."

Analysts have blamed the iPhone X's poor performance on what they see as its lack of interesting innovation and its high price.